In a series of five experiments, the study's authors examined how including a marker of politeness in a negative product review affected the image of both the reviewer and the product. For example, phrases like "I'll be honest" and "I don't want to be mean, but…" are ways to soften the arrival of bad news and warn a reader or listener that negative information is coming. [The Four-Letter Words That Could Sink Your Customer Service]

"Most of the research on consumer reviews has been on the content and volume of the message," the study's authors wrote. "Our research looks at how the politeness with which a particular message is communicated affects consumer opinions."

In one experiment, 125 University of Minnesota undergrads were asked to read a page-long description of a luxury wristwatch. Two versions of the product description were used, one of which added the polite customer complaint, "I don't want to be mean, but the band pinches a bit."

The experiment's results indicated that people were willing to pay more — $136 versus $95 — for the wristwatch if they read the description that included the politeness marker.

The study also asked participants to complete a survey evaluating the "personality" of the brand. Results showed that the review using the politeness marker caused the brand to be seen as more honest, cheerful, down-to-earth and wholesome than the same review without the polite customer complaint.

"Our research raises the intriguing possibility that brands might benefit when polite customers write reviews of their products -- even when those reviews include negative opinions," the authors said.

Emory University's Ryan Hamilton, the University of Minnesota's Kathleen Vohs and Ann McGill from the University of Chicago Booth School of Business authored the study.